This invention relates to a printer system for controlling a thermal fixing device which is provided as in a laser beam printer.
In recent years, the laser beam printers have been finding popular acceptance as means for printing character information and image information. The printers of this class are provided with a thermal fixing device for thermally fixing an image formed on a recording paper. As a heat source for the thermal fixing device, a heater lamp may be cited for example. By reason of heavy consumption of electric power, for example, and with due regard to the saving of energy, this heater lamp is controlled so as to decrease the supply of electric power to a level enough for retaining the heater lamp in a warm state or to suspend the supply while the heater lamp is not in use. Though this control is indeed effective in economizing the use of energy, it is on the contrary at a disadvantage in lacking the instantaneousness with which the printing operation is started immediately after the issuance of a command to print.
For the elimination of this disadvantage, therefore, the invention disclosed in JP-A-62-187,874, for example, contemplates starting the supply of electric power to the thermal fixing device on the condition that opposite communication channels are opened as when image data are transmitted from a host computer to a printer. Even this technique has a problem of incapability of immediately setting the printer to operation. To be specific, the operation of this technique entails a problem of inevitable attendance of an operator at the site of operation because the heating of the fixing device is started as triggered by the data transmitted immediately before the printing and, therefore, the time required for the reception of the data is relatively short.
The technique reported at pages 130 to 133 of the Sep. 13, 1993 issue of the "Nikkei Electronics," is aimed at curtailing the rise time by using a film fixing device having a small thermal capacity or curtailing the rise time of a heat roller type fixing device by varying a raw material for the roller or halving the wall thickness of the roller. Since these conventional techniques invariably entail a decrease in the thermal capacity of the relevant heating part, they tend to impair the evenness of heating and necessitate accurate control of temperature.